cricoarytenoid joints

Each cricoarytenoid joint is a synovial
joint; its cavity is surrounded by a capsular ligament lined with synovial
membrane. The movements allowed at the joint are: (1) gliding, by which
the arytenoid advances toward its fellow or retreats from it; (2) rotatory,
by which the arytenoid cartilage rotates around a vertical axis, swinging
the vocal process laterally or medially so as to open or close the rima
glottidis.

The capsule is strengthened posteriorly, and forward movement of the arytenoid
cartilage is thus restricted.